Performance tuning and third-party update

Tow major issues were identified in the last month which will be addressed in the upcoming weeks:

1. Performance: since shadows are a significant part of the engine's 3D renderer the CPU overhead was needed to be reduced. The result is 2x-4x speedup using VK_EXT_shader_viewport_index_layer or "math magic"  if the extension is not present. 
2. Vulnerability: some anti-virus software reported this application therefore a huge third party software update was performed on these: assimp-5.2.5, jpeg-9e, libpng-1.6.40, libtiff-4.5.1, libzip-1.9.2, lua-5.2.4, meshoptimizer-0.19. minimp3, ogg-1.3.5, qhull-2020.2, recastnavigation-1.6.0, v-hacd-4.1.0, vorbis-1.3.7, zlib-1.2.13. I hope this will help the situation.

  Minor updates:

• Fps counter added
• Erroneous sunshadow fixed with increased  shadow map depth bits
• DoF shader error fixed thanks to Mesa
• Forcing "bullet-time effect" at low fps removed 

The next plane is to profile and optimize the heavy GLSL shaders.